AN 8.63 4sp, 4bv, 4j all are part of "3 ways of samadhi" (
samādhi in 3 ways), and you can do any combination of those in all four postures. Also see
AN 3.63 for explicit tie between 4j and walking. AN 8.63 is like an expanded version of
SN 47.3 +
SN 47.4.